The present invention relates to a torque converter stator used in a motor vehicle transmission. A torque converter is principally constructed to have three wheels, namely an impeller or pump, a turbine and a stator. These three components are joined together and its interior is filled with transmission oil. The impeller is connected to an input shaft of the torque converter and converts rotary force from the engine into flow of the oil through centrifugal force. The turbine that is connected to an output shaft of the converter receives the flow of the oil from the impeller and converts it into torque. The stator changes the direction of the flow of the oil leaving the turbine before the oil returned to the impeller, so as to perform a function of increasing the transmitted torque.
The oil is a transmitting medium that circulates between the input side and output side of the torque converter. The impeller and turbine are connected to the input and output shafts of the converter and are allowed to slide relative to each other. These two parts function as a clutch so as to make it easy for the vehicle to be started and absorbs shocks. These advantages promote torque converters for wide use in passenger cars and other types of motor vehicles.
The stator is an important part of the torque converter and various designs have been utilized in the prior art to improve engine economy during coasting, anti-creep idling, and for improved acceleration.
The stator is designed with two considerations in mind. First, when the car is just starting or accelerating, the stator takes the fluid flow from the turbine and redirects fluid so that it will not slow down the impeller and work against the engine. Second, when the car is running with high operational transmission oil flow, the stator's job is to get out of the way and let the fluid flow naturally and unobstructed.
Prior art stator designs have attempted to improve upon stator blade design by providing for variable pitch stator blades. However, the prior art stators with variable pitch are complicated and subject to wear. Accordingly, it is an objective of the current invention to utilize a stator which provides the benefits of variable pitch stators but in a unit or member, preferably cast in one-piece.
Moreover, conventional hydraulic torque converters include a stator having a one-way clutch which, when it is locked to deflect oil back to the impeller from the turbine. When a sufficient speed ratio between the turbine and impeller is achieved (i.e., the turbine and the impeller are turning at almost the same speed), the one-way clutch of the stator assembly free-wheels because fluid coming from the turbine strikes the back side of the stator blades. Accordingly, an objective of the present invention is to utilize the benefits of a free-wheeling stator during both low and high transmission oil flow.
Stator blades encounter varying transmission oil centrifugal forces during operation. For example, during low speed operation the oil is relatively uniform throughout the entire expanse of the stator but during high transmission oil flow, the oil is directed to the outside of the stator by centrifugal force. Accordingly, it is a still further objective of the present invention to provide a stator design which utilizes the centrifugal forces encountered by a stator.
It is a further objective of the present invention to provide a torque converter which overcomes the disadvantages of the prior art.
It is a still further objective of the present invention to provide a stator which is a simplified form, and is therefore less costly in production and use.
These and other objectives will become apparent from the following description of the invention.